When, how and why is it important to "Stop off "tomato plants
Why Stop off Tomatoes
Tomatoes are a really vigorous plant and this is part of the reason we have to stop them growing at some point.
The image left shows how vigorous tomatoes are. This tomato plant is growing in the scant soil provided in a pavement crack in a city centre. The original seed probably came from a sandwich. If we leave tomato plants unchecked, it will grow many branches from the side shoots, it will grow taller and taller and become a mass of overgrown green. The extensive growth will be at the expense of the flowers and fruit. To get a good crop, it is necessary to constrain the plant.
When is the best time to stop off tomatoes?
In around August or September, (depending on where in the country your garden, and the growing season,) it is necessary to "stop off" the tomato plants. This means pinching out the growing tips at the top of the plant and stop the plant growing up any further. Stop off at the top of the plant when there are 3-4 (outside grown) and 4-5 (greenhouse grown) trusses, which are layers of flowers. The exact timing of when to stop the plant growing depends on when it has set enough trusses, which depends on growing conditions.
Continue taking out the growing points as the plant will strive to keep growing upwards. This means once you have cut off the top of the plant to stop it growing, you will need to do this again, and again, as it will keep trying to grow through the greenhouse ceiling.
How to stop off tomatoes
In this image, the plant is actually resting on the top of the greenhouse roof. Above the flower is the pane of glass forming the top of the roof, so the tomato plant has reached the roof and developed the maximum number of trusses.
The arrow points to the cut-off growth point. Within a couple of weeks, shoots will appear alongside the cutoff point as the tomato attempts to re grow, cut these off as well.
Thin out the leaves
Later in the season, thin out the tomato foliage which will divert the plant's energy into making fruits and not more and more leaves. Towards the end of the season, the plant shouldn't have masses of leaves on it. Be bold, cut them off. At the peak of the growing season, I remove lots of leaves each week when checking the tomatoes. The image shows a trug full and I may cut this amount off, towards the end of the growing season, every week to 10 days. This also aids ventilation, which helps to reduce the risk of diseases.
You may spot a few flowers in the cut-offs. Toward the end of the season, you will have to decide which flowers will come to maturity, and which to sacrifice, in order to get the other flowers and fruits to mature. It depends on your growing conditions when to consider this. When you feel the season is slowing down, and light levels are starting incrementally to fall, there is only limited time left for the fruits to swell and it's better to concentrate a few less fruits as not all will mature. Remove all flowers and tiny fruits that will not have time to mature.
Step-by-step guide
How to grow tomatoes from seed and what to do about weedy seedlings
What are the easiest tomatoes to grow? Cordon or Bush?
How to pot on tomatoes, dos and don'ts, and why it is important.
Hardening off tomatoes for growing outside
Pinching out Side Shoots on tomatoes
The Best way to Water and Feed Tomatoes
How to ripen Green Tomatoes
Common pest and diseases when growing tomatoes
Success with Tomatoes
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